Such a rotary tool can be seen, for example, from DE 10 2014 206 796.0 which was unpublished at the time of application.
The rotary tool, in particular a drill, is what is known as a modular rotary tool, which extends axially along a rotational axis and has two coupling elements, namely a support and a cutting head, said cutting head being interchangeably mounted on the support. For this purpose, the support typically has on its end face two opposite fastening flanges preferably separated from each other by flutes that delimit a pin receptacle. A coupling pin of the cutting head is inserted into this pin receptacle. This is done by rotating the cutting head about the rotational axis relative to the support. This rotation forms a clamping connection between the cutting head and the support, so that the two coupling elements are held clamped against each other. In particular, no other fastening means, such as screws or the like, are used. In this case, the pin receptacle of the support has inner sheath surfaces and the coupling pin of the cutting head has outer sheath surfaces which mutually act together. For this purpose, mutually corresponding clamping sections are formed on the inner sheath surfaces and the outer support surfaces for transmitting a radial clamping force. These lie against each other in pairs in the mounted state. Preferably, a corresponding torque section is formed in addition on the inner sheath surfaces and the outer sheath surfaces for transmitting torque. The cutting head is completely enclosed by the coupling recess, that is, by the two opposite clamping or securing flanges, so that both the torque sections and the terminal sections are thus enclosed by the securing flanges.
In alternative embodiments, the torque sections are not enclosed by the clamping flanges, but rather extend in the radial direction to an outer peripheral line of the rotary tool, so that a peripheral side of the coupling pin in the area of the torque section is aligned with a peripheral side of the support. Such a coupling connection is disclosed, for example, in DE 10 2012 212 146 A1. In this embodiment variation, the mutually corresponding surfaces of the torque section are designed to be inclined as an axial slide safety assembly.
In a rotary tool known from DE 10 2012 200 690 A1, the torque sections and the clamping sections of the coupling connection are arranged one after the other in the circumferential direction on the coupling pin and on the support. In this case, the coupling pin has a roughly cuboid shape, wherein fluted areas are cut out from the rectangular shape via flutes. For axial tightening and to prevent axial pullout, either the mutually corresponding clamping sections and/or the mutually corresponding torque sections form a dovetail joint. The corresponding sections are thus inclined with respect to the rotational axis.
A modified embodiment of the coupling connection is known from DE 10 2013 205 889 B3, taken from DE 10 2012 200 690 A1. In this case, the torque sections and the clamping sections are disposed offset from one another in the axial direction so that either torque sections or clamp sections are formed on one axial level. Also in this embodiment, a dovetail joint is formed by obliquely inclined torque sections or clamping sections to produce axial tightening and to prevent axial slippage.
By means of such a dovetail joint known from the prior art, an effective positive-fit connection is formed in the axial direction. Due to the special mounting method, this is made possible by screwing the coupling pin of the cutting head into the pin receptacle of the support.
In addition to these dovetail connections, stepped undercuts are also known for preventing axial pullout.
Thus, from U.S. Pat. No. 6,582,164, for example, radially outwardly projecting flanges are formed on the outer circumferential surfaces of the coupling pin which are screwed in the manner of a thread into a corresponding recess on the pin receptacle. For easy insertion, in this case, the lateral surfaces of these thread ridges are inclined obliquely relative to the axis of rotation.
A coupling connection can also be learned from U.S. Pat. No. 7,070,367 B2, wherein flanges are formed on the outside of the coupling pins which extend helically and form a screw thread. In this way the cutting head is axially tightened when screwed in. The helically extending flange in this case has a roof surfaces inclined to the rotational axis.
DE 10 2014 206 796.0, which was unpublished at the time of application, describes a further embodiment of the embodiment taken from DE 10 2012 200 690 A1. For an axial pullout safety device—except for any recesses present due to grooves—the essentially cuboid coupling pin has, instead of the dovetail joint, a circumferential flange on the end of the coupling pin which merges to form a step for clamping and torque surfaces. A horizontal stop surface is formed by the step which acts as an axial pullout safety device. The clamping surfaces are thereby formed by a radial groove.
A coupling connection is known from KR 10 2008 0000544 A in which only clamping surfaces are formed on the coupling pin and the torque surfaces are formed outside the coupling recess. For an axial pullout safety device, a circumferential groove is placed approximately centrally in the cylindrical-sheath-shaped coupling pin, and a corresponding flange on the support engages in it.
Overall, the known coupling connections are characterized by a complex geometry, which is often very expensive to produce.